Process and apparatus for producing shaped tobacco materials



ep 1970 'M. BERING E IR ETAL 3,529,605

PROCESS AND APPARATUS FOR PRODUCING SHAPED TOBACCO MATERIALS Filed March14. 1967 FIG] I INVENTORS MONIQUE BERINGER PAUL' BUCHMANN BY W IATTORNEYS United States Patent 3,529,605 PROCESS AND APPARATUS FORPRODUCING SHAPED TOBACCO MATERIALS Monique Beringer, St.-Louis, France,and Paul Buchmann, Basel, Switzerland, assignors to Tamag Basel A.G.Filed Mar. 14, 1967, Ser. No. 623,046 Claims priority, applicationSwitzerland, Mar. 16, 1966,

. 3,774/ 66; Mar. 10, 1967, 3,534/ 67 Int. Cl. A24b 3/14 US. Cl. 131'13315 Claims ABSTRACT OF THE DISCLOSURE A method and apparatus forproducing shaped tobacco materials, such as sheet-like, filamentous orstrand-like tobacco materials, comprising mixing and finely grinding atobacco material together with a liquid in a preferably continuouslyworking mill and shaping the ground material in a conventional manner.The brinding mill contains a stirrer which comprises a shaft havingrings arranged in spaced manner therealong in staggered relationship andwhich on being set into motion, coact with grinding balls within themill housing to secure homogenization of the tobacco. The temperaturerequired for obtaining the de sired adhesiveness of the mixture isadjusted by means of the frictional heat developed in the mill. A liquidis used having a determined pH value.

It is known that the particle size of tobacco or of the veins of tobaccoleaves used to produce shaped tobacco materials exert a substantialinfluence not only on the strength of the shaped tobacco material, butalso on the elasticity thereof. This is more particularly the case, if

shaped tobacco materials are to be produced either in the full absenceor in the presence of only small quantities of binders.

Furthermore it is known to grind tobacco in either a wet or dried formin order to get colloidal particle sizes of the tobacco material, whichis then suspended in water or in a solvent, whereupon large quantitiesof binding agents are added to the resultant suspension. Moreover, suchtobacco suspensions can be extracted under heating and, if desired,under pressure. The extract thus obtained can be mixed with furthertobacco fractions; in this latter case relatively small amounts ofbinding agents are added. However, all methods known up to now requireseveral operation steps which are complicated and uneconomical.

The main object of the present invention is the production of shapedtobacco products, such as sheet-like filamentous or strand-like tobaccoproducts and the like, preferably by using just one operation stepwithout requiring a substantial supply of energy and without usingexpensive apparatus. On the contrary, the new method of the presentinvention can be carried out with a minimum of working capacity.

According to the new method of this invention a tobacco material ismixed with a liquid and finely ground with the said liquid in at leastone operation step in a mill, which preferably works in a continuousway, the ground material being then converted in a conventional way intothe desired form.

The temperature required to develop the desired adhesiveness of thetobacco material can be furnished by the frictional heat produced in themill.

It has also been found that the pH value of the liquid to be used will,in general, depend on the kind and on the pH value of the tobaccomaterial (tobacco for cigars or cigarettes) which is to be treated.

In some cases it may be desirable to use small amounts of variousadditives in order to improve for instance the flavour of the smoke orthe water-in-solubility of the shaped tobacco product. In such cases thedesired additives can be added to the liquid and/or to the tobaccobefore grinding the mixture. This procedure permits a continuous workingmanner and does not require any pH control of the tobacco slurry duringthe manufacturing process.

The liquid to be used has normally a pH value ranging from 4 to 10inclusive. Preferably a pH value ranging from 6 to 10 inclusive and insome cases from 7.5 to 9 inclusive will give satisfactory results. Theliquid itself can be water or an aqueous solution of an acid, a base ora salt. A suitable base or salt respectively may be ammonia or potassiumhydrogen carbonate.

It has also been discovered that the properties of the shaped tobaccomaterial, like its flavour or its colour, can be influenced by suitableselection of the pH value of the liquid depending upon the tobacco type(light or dark tobacco), the pretreatment, such as the drying degree orfermentation degree, and/or upon the pH value of the tobacco materialused.

If desired, up to 3 percent by weight of a binding agent foreign to andnot present in the tobacco material, like methyl cellulose, ethylcellulose, sodium carboxy-methyl cellulose and the like, and/or up to 5percent by weight of a softening agent, such as glycerol, polyethyleneglycol and so on, can be added to the mixture of tobacco and liquid,before the said mixture is introduced into the mill. In some cases, alsoup to 2 percent by weight of a fibrous material, eg asbestos or thelike, can be added. Any one of these substances can also be added to thetobacco slurry flowing out of the mill.

It is preferred to use as starting material coarsely comminuted tobacco.It has been observed that it is advantageous to grind the mixtureconsisting of tobacco and liquid in a mill of the kind disclosed in thefollowing and shown on the drawing, until the mixture contains colloidalparticle sizes. Generally the mixture is wet ground in the mill whilehomogenizing the mixture and heating the same to at most C. due to thefrictional heat developed during the grinding operation. It is alsopossible to lower the temperature produced in the .mill by frictionalheat by cooling the mill in a conventional manner to a temperature belowor much below 100 C. The new method is most suitably carried out in onesingle step.

The warm tobacco slurry flowing out from the mill can be dried in aconventional manner in order to produce a shaped tobacco material.

The shaped tobacco material made according to the present invention canbe used as tobacco for cigarettes, cigars and pipes, i.e. as cuttobacco, cover or outer leaves, and as substitute for cigarette paper.

The present invention will now be described in more detail in thefollowing examples. However, the invention is not intended to be limitedeither to the following examples or to the drawing.

EXAMPLE 1 500 liters of water are introduced into a container and mixedwith 100 grams of potassium hydrogen carbonate to adjust the pH to avalue of about 8.5. After addition of 100 kg. of light tobacco (e.g.Virginia tobacco) the resultant suspension is introduced into acontinuously working mill by means of a metering pump and wet grounduntil the desired particle size has been reached. After a short startingperiod the temperature of the mixture increases without any externalheat to about 70 C. The grinding period is about 15 minutes. The stillwarm tobacco slurry flows out from the mill and is immediately dried andconverted into the desired form.

3 EXAMPLE 2 600 liters of water are introduced into a container and thepH value is adjusted to about 8.0 by adding 50 ml. of a 25% ammoniasolution. Then 100 kg. of dark tobacco (e.g. Java tobacco for cigars),2% of glycerol (based on the weight of the tobacco material used), 1 kg.of citric acid and 1.5 kg. of sodium carboxymethyl cellulose are addedto the solution. The mixture is introduced into a continuously workingmill by means of a dosage pump, homogenized and heated without externalheat, but merely by means of the frictional heat to the temper aturesuitable for causing the solution to react with the tobacco material.The wet ground tobacco slurry running out from the mill is immediatelydried and shaped.

A mill, which is particularly adapted for the performance of the newprocess and constitutes also an aspect of the present invention, willnow be described With reference to the accompanying drawing in whichFIG. 1 is a side elevation of the mill, the housing being shown insection and FIG. 2 is a sectional view along the line I--I of FIG. 1.

In a cylindrical housing 1 a stirring mechanism 2 is arranged,comprising a shaft 3 with a number of rings 4. The rings 4 are securedto the shaft 3 and disposed asymetrically, in spaced relationship, oneupon the other. The shaft 3 may be driven by a motor 9. In the housing 1an opening 5 is provided for the inlet of the material to be ground,which consists of a mixture of liquid and tobacco. A further opening 6is provided for the outlet of the ground material, this opening beingcovered by a screen 7. The housing is filled with small balls 10, whichmay be made of metal or any other suitable material. In a duct 11leading into the opening 5 a pump 12 is arranged.

The operation of the mill is as follows: By means of the pump 12 themixture of liquid and tobacco is fed through the opening 5 into thehousing 1, where it moves to the upper part of the housing, the shaft 3rotating at high speed. When passing the housing 1, which contains theafore-mentioned balls the tobacco particles are very finely ground and,at the same time, intimately mixed. The resulting frictional heat isused to cause the desired reaction between the tobacco material and theliquid. The exceeding heat can be dissipated by transmission to acooling fluid circulating in a cooling jacket 13 with inlet and outletconnections 14.

A mill as heretofore described is, for instance, the Molinex milloffered by Gebr. Netzsch, Selb, Germany, under the designations KE 5,20, 50 and 100.

What we claim is:

1. In a single-step continuous method for producing a wet ground tobaccoslurry from a mixture of coarsely comminuted tobacco and a member of thegroup consisting of Water and an aqueous solution, the improvementcomprising continuously grinding said mixture in a ball mill filled withsmall grinding balls and having a stirring tool consisting of a shaftwith rings asymetrically disposed therearound, whereby the temperaturerequired for obtaining the desired homogenization and adhesiveness ofsaid slurry is supplied solely by the friction created between saidrings and said grinding balls.

2. A method according to claim 1 comprising the use of an aqueoussolution having a determined pH value which is independent of the pHvalue of said slurry.

3. A method according to claim 1, comprising the use of an aqueoussolution having a pH value which is dependent upon the type of thetobacco to be treated,

4. A method according to claim 1 comprising the use of an aqueoussolution having a pH value ranging from 4 to 10 inclusive.

-5. A method according to claim 4, comprising the use of an aqueoussolution having a pH value ranging from 7.5 to 9.

6. A method according to claim 1 wherein the aqueous solution isselected from the group consisting of an aqueous acid solution, anaqueous base solution and an aqueous salt solution.

7. A method according to claim 1 wherein said mixture of tobacco andaqueous solution also includes up to 3% by weight of a binding agentforeign to tobacco taken from a group consisting of methyl cellulose,ethyl cellulose and sodium carboxy-methyl cellulose and up to 5% byweight of a softening agent taken from a group consisting of glyceroland polyethylene glycol.

8. A method according to claim 1, wherein said mixture consisting oftobacco and aqueous solution also includes up to 2% by weight of afibrous material.

9. A method according toclaim 1, comprising grinding the mixtureconsisting of tobacco and aqueous solution to a colloidal particle size.

10. A method according to claim 1 comprising lowering the temperature inthe mill due to frictional heat, by cooling to a temperature below C.

11. A method according to claim '1 wherein said mixture remains in saidmill for a time not exceeding 15 minutes.

12. A mill for use in the single-step continuous production of a Wetground tobacco slurry from a mixture of coarsely comminuted tobacco anda member of the group consisting of water and an aqueous solution, saidmill comprising a housing, said housing having an inlet opening for saidtobacco and said water or aqueous solution and an outlet opening forsaid slurry, a stirrer within said housing consisting of a shaft havingrings arranged therealong in a spaced manner and in staggeredrelationship against each other with respect to the center thereof, saidhousing being filled with grinding balls which are set into motion bysaid rings, whereby the temperature required for obtaining the desiredhomogenization and adhesiveness of said slurry is supplied solely by thefriction created between said rings and said grinding balls.

13. A mill as claimed in claim 12 wherein said rings are staggeredagainst each other in an asymmetric manner such that said stirrer doesnot produce any static imbalance.

14. A mill as claimed in claim 12 wherein said housing is surrounded bya cooling jacket provided with an inlet opening and an outlet openingfor a cooling medium.

15. A mill as claimed in claim 12 wherein said inlet opening is arrangedin the bottom part of said housing and said outlet opening is arrangedin the upper part of said housing.

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